1. Field of the Invention
This invention relates to a surface modifying agent which provides fillers when subjected to a surface modifying treatment with it with water-repellent property, processability in resin and the like.
2. Discussion of the Background
Titanate base coupling agents are commonly known as surface treating agents which provide fillers with water repellency, reduced oil adsorption, dispersibility in resin, processability and the like by regulating surface energy of inorganic fillers and the like. When it is necessary to improve dispersibility, processability and the like of fillers in an organic matrix such as a resin, an organic solvent or the like, such improvements may be obtained by selecting a coupling agent which is fit for the wettability of relevant organic matrix, and various coupling agents fit for to various organic matrices are available. For example, a titanate base coupling agent having side chains of low polarity is used for low polarity resins such as polyolefin, and a high polarity agent for high polarity resins such as polyamide.
On the other hand, methods of the surface treatment of fillers with coupling agents is roughly divided into two categories, namely a pretreatment one in which a filler is treated with a coupling agent in advance before mixed with an organic matrix, and an integral blend one in which a coupling agent is added when a filler is mixed with an organic matrix. Since the integral blend method is somewhat low in treating efficiency, its use is limited to the field of coating materials and the like. The pretreatment method is further divided into a dry method in which a filler and a coupling agent are directly mixed using a mixer or the like and a wet method in which both components are treated in a solvent and the solvent is removed later, and the wet method is, in turn, divided into an organic solvent method in which an organic solvent is used and a water treatment method in which the treatment is carried out in water. Of these, the dry method is most commonly used, but is slightly inferior in surface treatment effect to the wet method. This is considered to be due, probably, to the incomplete mixing of the coupling agent with the other component. In addition, the dry method is not suitable for the treatment of fragile fillers such as hollow fillers, needle fillers and the like, because a mixer having a large shear is used therein. The organic solvent method is reliable with regard to the surface treatment of fillers, but there is a tendency to avoid its use due to the recently increasing organic solvent regulation.
The water treatment method is free from such organic solvent regulation and can effect uniform treatment under mild mixing conditions, but water soluble coupling agents are rare and, as a matter of course, no water soluble agents which can cope with low polarity organic matrixes have been known. In order to solve such a problem, a means to make a coupling agent into a water dispersible form by its joint use with a surface active agent has been disclosed, for example, in Ken-React Reference Manual (1985) published by Kenrich Petrochemicals Inc., and Japanese Patent Application Laying-Open (Kokai) No. Hei 04-25568. However, the surface active agents described in these references when mixed with a titanium base or the like coupling agent and preserved, react with the coupling agent with the lapse of time, hence entailing a considerable decrease in emulsification capacity of the agent with water. In consequence, such a means results in a problem with regard to the preservation stability when a one-pack type coupling agent is made by blending a coupling agent with a surface active agent in advance.